Generally, in order to check the amount of etching, which is an important quality item of a wafer-etching process, it is necessary to measure the thickness of a wafer to be etched.
The thickness of the wafer is measured using thickness measurement equipment before a wafer-etching process, and after the wafer is etched using etching equipment, the thickness of the wafer is again measured.
The thickness of the wafer may be measured using a difference in electric capacity, which depends on a gap between a target, i.e. the wafer, and an electric-capacity-measuring probe by forming an electric field between the wafer and the electric-capacity-measuring probe.
As described above, the thickness of the wafer is generally measured using separate thickness measurement equipment before and after wafer etching in order to check the amount of etching. However, such duplicate thickness measurements may incur time and labor losses.